[libc][math][c23] Add f16sub C23 math function

Author: overmighty

libc/config/linux/aarch64/entrypoints.txt

@@ -512,6 +512,7 @@ if(LIBC_TYPES_HAS_FLOAT16)
     libc.src.math.f16divf
     libc.src.math.f16fmaf
     libc.src.math.f16sqrtf
+    libc.src.math.f16sub
     libc.src.math.f16subf
     libc.src.math.fabsf16
     libc.src.math.fdimf16

libc/config/linux/x86_64/entrypoints.txt

@@ -545,6 +545,7 @@ if(LIBC_TYPES_HAS_FLOAT16)
     libc.src.math.f16fmaf
     libc.src.math.f16fmal
     libc.src.math.f16sqrtf
+    libc.src.math.f16sub
     libc.src.math.f16subf
     libc.src.math.fabsf16
     libc.src.math.fdimf16

libc/docs/math/index.rst

@@ -130,7 +130,7 @@ Basic Operations
 +------------------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
 | f16fma           | |check|          | |check|         | |check|                | N/A                  | |check|                | 7.12.14.5              | F.10.11                    |
 +------------------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
-| f16sub           | |check|          |                 |                        | N/A                  |                        | 7.12.14.2              | F.10.11                    |
+| f16sub           | |check|          | |check|         |                        | N/A                  |                        | 7.12.14.2              | F.10.11                    |
 +------------------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
 | fabs             | |check|          | |check|         | |check|                | |check|              | |check|                | 7.12.7.3               | F.10.4.3                   |
 +------------------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+

libc/spec/stdc.td

@@ -734,6 +734,7 @@ def StdC : StandardSpec<"stdc"> {
           GuardedFunctionSpec<"f16addl", RetValSpec<Float16Type>, [ArgSpec<LongDoubleType>, ArgSpec<LongDoubleType>], "LIBC_TYPES_HAS_FLOAT16">,
           GuardedFunctionSpec<"f16addf128", RetValSpec<Float16Type>, [ArgSpec<Float128Type>, ArgSpec<Float128Type>], "LIBC_TYPES_HAS_FLOAT16_AND_FLOAT128">,
 
+          GuardedFunctionSpec<"f16sub", RetValSpec<Float16Type>, [ArgSpec<DoubleType>, ArgSpec<DoubleType>], "LIBC_TYPES_HAS_FLOAT16">,
           GuardedFunctionSpec<"f16subf", RetValSpec<Float16Type>, [ArgSpec<FloatType>, ArgSpec<FloatType>], "LIBC_TYPES_HAS_FLOAT16">,
 
           GuardedFunctionSpec<"f16divf", RetValSpec<Float16Type>, [ArgSpec<FloatType>, ArgSpec<FloatType>], "LIBC_TYPES_HAS_FLOAT16">,

libc/src/math/CMakeLists.txt

@@ -113,6 +113,7 @@ add_math_entrypoint_object(f16fmaf128)
 
 add_math_entrypoint_object(f16sqrtf)
 
+add_math_entrypoint_object(f16sub)
 add_math_entrypoint_object(f16subf)
 
 add_math_entrypoint_object(fabs)

libc/src/math/f16sub.h

@@ -0,0 +1,20 @@
+//===-- Implementation header for f16sub ------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC_MATH_F16SUB_H
+#define LLVM_LIBC_SRC_MATH_F16SUB_H
+
+#include "src/__support/macros/properties/types.h"
+
+namespace LIBC_NAMESPACE {
+
+float16 f16sub(double x, double y);
+
+} // namespace LIBC_NAMESPACE
+
+#endif // LLVM_LIBC_SRC_MATH_F16SUB_H

libc/src/math/generic/CMakeLists.txt

@@ -3828,6 +3828,19 @@ add_entrypoint_object(
     -O3
 )
 
+add_entrypoint_object(
+  f16sub
+  SRCS
+    f16sub.cpp
+  HDRS
+    ../f16sub.h
+  DEPENDS
+    libc.src.__support.macros.properties.types
+    libc.src.__support.FPUtil.generic.add_sub
+  COMPILE_OPTIONS
+    -O3
+)
+
 add_entrypoint_object(
   f16subf
   SRCS

libc/src/math/generic/f16sub.cpp

@@ -0,0 +1,19 @@
+//===-- Implementation of f16sub function ---------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/math/f16sub.h"
+#include "src/__support/FPUtil/generic/add_sub.h"
+#include "src/__support/common.h"
+
+namespace LIBC_NAMESPACE {
+
+LLVM_LIBC_FUNCTION(float16, f16sub, (double x, double y)) {
+  return fputil::generic::sub<float16>(x, y);
+}
+
+} // namespace LIBC_NAMESPACE

libc/test/src/math/CMakeLists.txt

@@ -1941,6 +1941,19 @@ add_fp_unittest(
     libc.src.math.f16addl
 )
 
+add_fp_unittest(
+  f16sub_test
+  NEED_MPFR
+  SUITE
+    libc-math-unittests
+  SRCS
+    f16sub_test.cpp
+  HDRS
+    SubTest.h
+  DEPENDS
+    libc.src.math.f16sub
+)
+
 add_fp_unittest(
   f16subf_test
   NEED_MPFR

libc/test/src/math/f16sub_test.cpp

@@ -0,0 +1,13 @@
+//===-- Unittests for f16sub ----------------------------------------------===/
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "SubTest.h"
+
+#include "src/math/f16sub.h"
+
+LIST_SUB_TESTS(float16, double, LIBC_NAMESPACE::f16sub)